As children head back to school, Rural Women NZ hopes 2014 will be the year when state-of-the-art signage will be approved for use on school buses to help remind passing motorists that "Either Way It's 20K".

Rural Women NZ national president Wendy McGowan said the 20kmh speed limit in both directions must be one of the most flouted rules in the Road Code, often because drivers are simply unaware of the law or don't notice they were passing a school bus until it was too late.

"We are calling for illuminated 20K signs to be approved for use on school buses," she said.

During 2013 Rural Women NZ took part in an extensive trial in Ashburton, along with TERNZ Ltd and NZTA, to alert drivers that they were about to pass a school bus and of the need to slow right down, called "Either Way it's 20K".

A key part of the trial was the installation of bright, 20K signs on the front and rear of the buses that lit up when the doors opened, and included flashing wig wag lights to attract drivers' attention well in advance.

The three-phase trial began with an intense awareness campaign, followed by targeted police enforcement.

According to Ms McGowan, the trial shows there's still a way to go.

"Before the campaign began, the average speed of drivers passing a stationary school bus was 80kmh. Now drivers are slowing to an average of 40kmh, with a noticeable speed reduction on main roads and open rural highways," she said.

"Children are especially vulnerable in rural areas, where they are dropped off at the side of the road, often with no pavement.

"A moment's inattention or the child's inability to translate speed and distance has led to tragic fatalities and serious injuries year on year as children dash in front of cars and trucks.

"Rural communities are right behind this campaign, and some have started fundraising for signs on their local school buses.

"We are just waiting for them to become an approved sign. In the long term we'd like to see 20K signs installed on all school buses throughout the country."